Conventional magnetic resonance imaging has good sensitivity for detecting breast lesions but its specificity is inadequate. High spectral and spatial resolution (HISS) Magnetic Resonance Imaging (MRI) of water and fat signals is a new approach that may increase both sensitivity and specificity of MRI. HiSS MRI equals or exceeds the spatial resolution of conventional MRI and provides detailed spectra of the water and fat in each voxel. The water and fat lineshapes are analyzed to produce images proportional to resonance linewidth, peak height, integral, changes following contrast media injection, and other parameters. HiSS MRI images are acquired with clinically acceptable run times using echo-planar spectroscopic methods. Previous work in this laboratory demonstrated quantitatively that contrast, edge delineation, and sensitivity to contrast agents in breast images derived from HiSS data are improved compared to conventional images. Although these results are promising, the methods used for data acquisition and processing were not optimal. In addition, there has been very limited experience with imaging small breast lesions. Therefore, the present application proposes technical improvements to HiSS and tests of the method for imaging small breast lesions in women who are later biopsied. Technical improvements to HiSS imaging: Data acquisition rates will be increased by sampling two lines of k-space in parallel. Improved data filtering methods and corrections for errors in k-space sampling will be implemented. Methods for generating images of Fourier components of the water resonance in each voxel will be developed and tested. Scans of small breast lesions: HiSS will be incorporated into the clinical breast imaging protocol used at the University of Chicago. In women who are known to have small breast lesions based on mammographic findings, HiSS scans will be performed before contrast media injection, at 3 minutes after contrast media injection, and at 20 minutes after injection. Images derived from HiSS datasets will be quantitatively compared to conventional images to determine whether HiSS improves sensitivity to features of lesions that are associated with malignancies, such as spiculations and inhomogeneous contrast media uptake. In addition the experiments will determine whether addition of HiSS imaging to clinical scans significantly improves sensitivity and specificity.